refactor: Move implies into moxlib

lib/service/xmpp.dart

@@ -35,6 +35,7 @@ import "package:get_it/get_it.dart";
 import "package:connectivity_plus/connectivity_plus.dart";
 import "package:flutter_secure_storage/flutter_secure_storage.dart";
 import "package:moxplatform/moxplatform.dart";
+import "package:moxlib/moxlib.dart";
 
 import "package:logging/logging.dart";
 import "package:permission_handler/permission_handler.dart";

lib/shared/helpers.dart

@@ -134,11 +134,6 @@ T? firstNotNull<T>(List<T?> items) {
   return null;
 }
 
-/// The mathematical a -> b
-bool implies(bool a, bool b) {
-  return !a || b;
-}
-
 /// Attempt to guess a mimetype from its file extension
 String? guessMimeTypeFromExtension(String ext) {
   switch (ext) {